1 /*
2 * symbols.c: in-kernel printing of symbolic oopses and stack traces.
3 *
4 * Copyright 2002 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
5 *
6 * ChangeLog:
7 *
8 * (25/Aug/2004) Paulo Marques <pmarques@grupopie.com>
9 * Changed the compression method from stem compression to "table lookup"
10 * compression (see tools/symbols.c for a more complete description)
11 */
12
13 #include <xen/symbols.h>
14 #include <xen/kernel.h>
15 #include <xen/init.h>
16 #include <xen/lib.h>
17 #include <xen/string.h>
18 #include <xen/spinlock.h>
19 #include <xen/virtual_region.h>
20 #include <public/platform.h>
21 #include <xen/guest_access.h>
22 #include <xen/errno.h>
23
24 #ifdef SYMBOLS_ORIGIN
25 extern const unsigned int symbols_offsets[];
26 #define symbols_address(n) (SYMBOLS_ORIGIN + symbols_offsets[n])
27 #else
28 extern const unsigned long symbols_addresses[];
29 #define symbols_address(n) symbols_addresses[n]
30 #endif
31 extern const unsigned int symbols_num_syms;
32 extern const u8 symbols_names[];
33
34 extern const struct symbol_offset symbols_sorted_offsets[];
35
36 extern const u8 symbols_token_table[];
37 extern const u16 symbols_token_index[];
38
39 extern const unsigned int symbols_markers[];
40
41 /* expand a compressed symbol data into the resulting uncompressed string,
42 given the offset to where the symbol is in the compressed stream */
symbols_expand_symbol(unsigned int off,char * result)43 static unsigned int symbols_expand_symbol(unsigned int off, char *result)
44 {
45 int len, skipped_first = 0;
46 const u8 *tptr, *data;
47
48 /* get the compressed symbol length from the first symbol byte */
49 data = &symbols_names[off];
50 len = *data;
51 data++;
52
53 /* update the offset to return the offset for the next symbol on
54 * the compressed stream */
55 off += len + 1;
56
57 /* for every byte on the compressed symbol data, copy the table
58 entry for that byte */
59 while(len) {
60 tptr = &symbols_token_table[ symbols_token_index[*data] ];
61 data++;
62 len--;
63
64 while (*tptr) {
65 if(skipped_first) {
66 *result = *tptr;
67 result++;
68 } else
69 skipped_first = 1;
70 tptr++;
71 }
72 }
73
74 *result = '\0';
75
76 /* return to offset to the next symbol */
77 return off;
78 }
79
80 /* find the offset on the compressed stream given and index in the
81 * symbols array */
get_symbol_offset(unsigned long pos)82 static unsigned int get_symbol_offset(unsigned long pos)
83 {
84 const u8 *name;
85 int i;
86
87 /* use the closest marker we have. We have markers every 256 positions,
88 * so that should be close enough */
89 name = &symbols_names[ symbols_markers[pos>>8] ];
90
91 /* sequentially scan all the symbols up to the point we're searching for.
92 * Every symbol is stored in a [<len>][<len> bytes of data] format, so we
93 * just need to add the len to the current pointer for every symbol we
94 * wish to skip */
95 for(i = 0; i < (pos&0xFF); i++)
96 name = name + (*name) + 1;
97
98 return name - symbols_names;
99 }
100
is_active_kernel_text(unsigned long addr)101 bool is_active_kernel_text(unsigned long addr)
102 {
103 return !!find_text_region(addr);
104 }
105
symbols_lookup(unsigned long addr,unsigned long * symbolsize,unsigned long * offset,char * namebuf)106 const char *symbols_lookup(unsigned long addr,
107 unsigned long *symbolsize,
108 unsigned long *offset,
109 char *namebuf)
110 {
111 unsigned int i, low, high, mid;
112 unsigned long symbol_end = 0;
113 const struct virtual_region *region;
114
115 namebuf[KSYM_NAME_LEN] = 0;
116 namebuf[0] = 0;
117
118 region = find_text_region(addr);
119 if (!region)
120 return NULL;
121
122 if (region->symbols_lookup)
123 return region->symbols_lookup(addr, symbolsize, offset, namebuf);
124
125 /* do a binary search on the sorted symbols_addresses array */
126 low = 0;
127 high = symbols_num_syms;
128
129 while (high-low > 1) {
130 mid = (low + high) / 2;
131 if (symbols_address(mid) <= addr) low = mid;
132 else high = mid;
133 }
134
135 /* search for the first aliased symbol. Aliased symbols are
136 symbols with the same address */
137 while (low && symbols_address(low - 1) == symbols_address(low))
138 --low;
139
140 /* Grab name */
141 symbols_expand_symbol(get_symbol_offset(low), namebuf);
142
143 /* Search for next non-aliased symbol */
144 for (i = low + 1; i < symbols_num_syms; i++) {
145 if (symbols_address(i) > symbols_address(low)) {
146 symbol_end = symbols_address(i);
147 break;
148 }
149 }
150
151 /* if we found no next symbol, we use the end of the section */
152 if (!symbol_end)
153 symbol_end = is_kernel_inittext(addr) ?
154 (unsigned long)_einittext : (unsigned long)_etext;
155
156 *symbolsize = symbol_end - symbols_address(low);
157 *offset = addr - symbols_address(low);
158 return namebuf;
159 }
160
161 /*
162 * Get symbol type information. This is encoded as a single char at the
163 * beginning of the symbol name.
164 */
symbols_get_symbol_type(unsigned int off)165 static char symbols_get_symbol_type(unsigned int off)
166 {
167 /*
168 * Get just the first code, look it up in the token table,
169 * and return the first char from this token.
170 */
171 return symbols_token_table[symbols_token_index[symbols_names[off + 1]]];
172 }
173
xensyms_read(uint32_t * symnum,char * type,unsigned long * address,char * name)174 int xensyms_read(uint32_t *symnum, char *type,
175 unsigned long *address, char *name)
176 {
177 /*
178 * Symbols are most likely accessed sequentially so we remember position
179 * from previous read. This can help us avoid the extra call to
180 * get_symbol_offset().
181 */
182 static unsigned int next_symbol, next_offset;
183 static DEFINE_SPINLOCK(symbols_mutex);
184
185 if ( *symnum > symbols_num_syms )
186 return -ERANGE;
187 if ( *symnum == symbols_num_syms )
188 {
189 /* No more symbols */
190 name[0] = '\0';
191 return 0;
192 }
193
194 spin_lock(&symbols_mutex);
195
196 if ( *symnum == 0 )
197 next_offset = next_symbol = 0;
198 if ( next_symbol != *symnum )
199 /* Non-sequential access */
200 next_offset = get_symbol_offset(*symnum);
201
202 *type = symbols_get_symbol_type(next_offset);
203 next_offset = symbols_expand_symbol(next_offset, name);
204 *address = symbols_address(*symnum);
205
206 next_symbol = ++*symnum;
207
208 spin_unlock(&symbols_mutex);
209
210 return 0;
211 }
212
symbols_lookup_by_name(const char * symname)213 unsigned long symbols_lookup_by_name(const char *symname)
214 {
215 char name[KSYM_NAME_LEN + 1];
216 #ifdef CONFIG_FAST_SYMBOL_LOOKUP
217 unsigned long low, high;
218 #else
219 uint32_t symnum = 0;
220 char type;
221 unsigned long addr;
222 int rc;
223 #endif
224
225 if ( *symname == '\0' )
226 return 0;
227
228 #ifdef CONFIG_FAST_SYMBOL_LOOKUP
229 low = 0;
230 high = symbols_num_syms;
231 while ( low < high )
232 {
233 unsigned long mid = low + ((high - low) / 2);
234 const struct symbol_offset *s;
235 int rc;
236
237 s = &symbols_sorted_offsets[mid];
238 (void)symbols_expand_symbol(s->stream, name);
239 /* Format is: [filename]#<symbol>. symbols_expand_symbol eats type.*/
240 rc = strcmp(symname, name);
241 if ( rc < 0 )
242 high = mid;
243 else if ( rc > 0 )
244 low = mid + 1;
245 else
246 return symbols_address(s->addr);
247 }
248 #else
249 do {
250 rc = xensyms_read(&symnum, &type, &addr, name);
251 if ( rc )
252 break;
253
254 if ( !strcmp(name, symname) )
255 return addr;
256
257 } while ( name[0] != '\0' );
258
259 #endif
260 return 0;
261 }
262
263 /*
264 * Local variables:
265 * mode: C
266 * c-file-style: "BSD"
267 * c-basic-offset: 4
268 * tab-width: 4
269 * indent-tabs-mode: nil
270 * End:
271 */
272